Police are under fire on Friday after a local news report revealed they held back key information about a ruling party lawmaker suspected of involvement in alleged online opinion rigging during a media briefing on the ongoing probe.

Police have been investigating suspected deliberate manipulation, led by a power blogger nicknamed Druking, of Internet comments posted in a news article carried out by web portal Naver.

Druking and two others allegedly used a software program to jack up the number of clicks in support of critical comments about the liberal Moon Jae-in government, in an apparent attempt to boost negative public sentiment.

With the local elections less than two months away, the scandal has stirred up a fierce political wrangling between the ruling Democratic Party and rival opposition, as Rep. Kim Kyoung-soo of the ruling party has known and been in contact with Druking for years.

On Monday, Seoul Metropolitan Police Agency Commissioner Lee Ju-min told reporters Kim barely read any of the messages Druking sent via Telegram messenger. Lee also said Kim only left formal replies, such as "Thank you," to the blogger.

Local broadcaster SBS reported late Thursday, however, that Kim had sent Druking at least 10 messages that contained the web addresses, or URLs, of news articles related to the president from November 2016 until last month.

Druking is said to have replied saying things like, "Yes, I have got it."

The blunder by the Seoul police agency is likely to add fuel to the oppositions' calls for a launch of a special counsel into the mounting allegations. The main opposition Liberty Korea Party submitted bills on Tuesday for special probes into the scandal, raising suspicions that Druking could have also led a similar scheme to sway voters in favor of Moon ahead of the snap presidential election in May of last year.

Police have already been blamed for trying to tone down the whole investigation because it involves the president and lawmaker Kim, one of Moon's closest confidants. Kim is running for a provincial governor post in the June elections.

Druking, once known as an ardent supporter of Moon, is suspected of becoming hostile and carrying out the comment rigging after the lawmaker Kim refused his request for jobs at government offices. He has denied the suspicion, saying he wanted to make it look like conservatives did it.

Police have arrested and indicted three suspects, including Druking, on the charge of obstruction of business.